<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>垂直手风琴</title>
    <link rel="stylesheet" href="style.css">
</head>
<body>
     <ul class="accordion">
        <li>
            <input type="radio" name="item" id="item1">
            <label for="item1">一级标题1</label>
            <ol>
                <li>二级标题1</li>
                <li>二级标题2</li>
            </ol>
        </li>
        <li>
            <input type="radio" name="item" id="item2">
            <label for="item2">一级标题2</label>
            <ol>
                <li>二级标题1</li>
                <li>二级标题2</li>
            </ol>
        </li>
        <li>
            <input type="radio" name="item" id="item3">
            <label for="item3">一级标题3</label>
            <ol>
                <li>二级标题1</li>
                <li>二级标题2</li>
            </ol>
        </li>
        <li>
            <input type="radio" name="item" id="item4">
            <label for="item4">一级标题4</label>
            <ol>
                <li>二级标题1</li>
                <li>二级标题2</li>
            </ol>
        </li>
     </ul>
</body>
</html>